Date of Award

5-9-2026

Thesis Type

Masters

Document Type

Dissertation

Divisions

Faculty of Medicine

Department

Department of Medical Microbiology

Institution

Universiti Malaya

Abstract

The genus Mycobacterium encompasses several pathogenic species including members of the Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacteria (NTM). Fluorochrome smear microscopy is the recommended method for the direct detection of mycobacteria. However, the diagnostic utility of auramine O smear microscopy (AOSM) for detecting NTM, particularly in comparison with MTBC, in adult Asian clinical samples has not been comprehensively evaluated. Hence, this study aimed to evaluate the diagnostic utility of AOSM for the direct detection of NTM versus MTBC, to identify independent predictors of AOSM positivity and to assess the clinical utility of AOSM in NTM disease management in an adult Asian patient population. This was a 5- year retrospective study conducted at Universiti Malaya Medical Centre. All samples from adult patients aged ≥ 18 years that underwent mycobacterial testing from 1 January 2018 to 31 December 2022 were included in the diagnostic utility analysis. NTM culturepositive adults with suspected NTM disease were included in the analysis of independent predictors of AOSM positivity while those with culture-confirmed NTM disease were included in the clinical utility analysis. Of 12,016 adult samples that underwent mycobacterial testing, 19.0% (n = 2,288) were culture positive. NTM and MTBC accounted for 50.2% (n = 1,149) and 49.8% (n = 1,139) of the mycobacterial isolates, respectively. AOSM demonstrated high specificity and negative predictive value (NPV) but exhibited very low sensitivity and positive predictive value (PPV) for detecting NTM. The sensitivity, specificity, PPV and NPV of AOSM for detecting NTM were lower than those for MTBC. Independent predictors of AOSM positivity were culture-confirmed NTM disease (aOR, 4.87; 95% CI, 1.35-17.53; p = .015) and an extrapulmonary sample type (aOR, 4.37; 95% CI, 1.25-15.22; p = .021). Of 204 adults with suspected NTM disease, 58 (28.4%) were eventually diagnosed with culture-confirmed NTM disease, of which only 1 (1.7%) was clinically suspected of having NTM disease and 40 (69%) were initially misdiagnosed as having TB based on AOSM results. In settings with a higher burden of TB than NTM disease, AOSM-positive adults with a history suggestive of TB should be considered for anti-TB treatment initiation. While AOSM showed limited clinical utility in NTM disease management, it may have a potential role as a supportive laboratory tool for differentiating NTM disease from colonisation, particularly in extrapulmonary samples.

Initial

khm

Additional Information

Dissertation (M.A.) – Faculty of Medicine, Universiti Malaya, 2026.

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